Priming apparatus for centrifugal pumps



Aug. 28, 1934. A. c. DURDIN, JR

PRIMING AIPARATUS FOR CENTRIFUGAL PUMPS Filed Dec. 12. 1932 Z .9 WW ws Patented Aug. 28, 1934 PRIMING APPARATUS FOR CENTRIFUGAL PUMPS Augustus C. Durdin, Jiz, Chicago, 111., assignor to Chicago Pump Company, Chicago, 111., a corporation of Illinois Application December 12, 1932, Serial No. 646,776

6 Claims.

The invention relates to priming apparatus for centrifugal pumps, and among its objects are to prevent surging of the water and to minimize the work of the priming or vacuum pump after the centrifugal pump has been primed. Another object is to simplify the construction of priming apparatus of this character. Another object is to provide adjustment means for regulating the suction after the centrifugal pump has been primed.

Occasionally when centrifugal pumps are being primed, at the inlet to the centrifugal pump, the vacuum produced by the priming pump is so great that the water floods the float chamber of the priming apparatus, and some of the water passes on to the priming pump, which is very objectionable and likely to damage the priming pump, and one of the objects of this invention is to prevent occurrence of this kind. Sometimes the water rises and falls causing a surging action in the priming apparatus and an object is to eliminate this objectionable condition.

With these and other objects and advantages in view, this invention consists in the several novel features hereinafter fully set forth and claimed.

The invention is clearly illustrated in the drawing accompanying this specification in which:

Fig. 1 is a view partly in side elevation and partly in central vertical longitudinal section of priming apparatus embodying a simple form of the present invention;

Fig. 2 is a vertical cross section taken on the line 2-2 of Fig. 1;

Fig. 3 is an enlarged detail vertical section of a certain regulating valve taken on the line 3-3 of Fig. 1;

Fig. 4 is a detail vertical section illustrating a modified form of venting means;

Fig. 5 is a horizontal section taken on the line '5-5 of Fig. 4, and

Fig. 6 is a detail vertical section illustrating a second modified form of venting means.

Referring to said drawing and first to Figs. -1 to 3 inclusive, which illustrate the preferred embodiment of the invention, the reference character 7 designates a centrifugal pump of conventional form having an inlet chamber 8 which is connected to an inlet pipe 9 by an elbow 9. The inlet pipe leads down to a lower source of water supply. The'impeller 10 of the centrifugal pump is mounted on a shaft 11, usually driven by an electric motor 12. As shown, the centrifugal pump is carried by a bracket 12 mounted on the motor 12.

Associated with the centrifugal pump is a vac.- uum or gas pump 13 usually of the type employing throwing water or make up water for its pumping action, and as shown the casing 13 of the vacuum pump is bolted to the casing 14 of the centrifugal pump. The impeller 13 of the vacuum pump is usually mounted on the shaft 11.

A suction conduit 15 leads from the suction side of the vacuum pump and communicates with the inlet chamber 8 of the centrifugal pump through a float chamber 16. Desirably the suction conduit leads over the top of the float chamher and communicates therewith through a port 17 in the wall 18 between the conduit and float chamber, which port is controlled by an upwardly opening check valve 19 which closes whenever the vacuum pump is rendered ineffective or partly ineffective, which happens when the centrifugal pump is primed. The float chamber communicates with-the inlet chamber of the centrifugal pump through a narrow passage 20 (see Fig. 2) which tends to retard the flow of water into the float chamber while the centrifugal pump is being primed.

To relieve the vacuum pump when the centrifugal pump has been primed, a relief valve 21 is provided for the suction conduit 15 and controls a port 22 which connects the suction conduit with the outer atmosphere. The relief valve 21 is connected by a float rod 24 to a float 23 contained in the float chamber 16. The relief valve remains closed until the water enters the float chamber and lifts the float, and when this occurs, outside air is admitted to the suction conduit and the vacuum pump is relieved or parvacuum in the suction conduit is broken, a small amount of air may enter the floatchamber through the orifice 28. Admission of a small amount of air to the float chamber permits the level of the water therein to lower slightly, thereby closing or partly closing the relief valve 21 and very quickly establishing a balanced condition wherein the vacuum maintained in the float chamber is suflicient to keep the level of the water therein practically constant. The ideal condition is one in which the float opens the relief valve sufficiently to relieve the vacuum pump so that it will not build up an unnecessarily high vacuum, but will hold the necessary vacuum in the float chamber to keep the level of the water therein substantially constant. By providing an orifice of proper size this ideal condition can be maintained. For this reason means are provided for regulating the size of the orifice 28 which means desirably may comprise a needle valve 25 threadedlyemounted in a bushing 26 secured in the top wall 18 of the conduit 15. The orifice 28 is desirably formed in a bushing 27 secured in the wall 18, and the needle valve may be used to regulate the size of the orifice by properly adjusting the valve.

In the operation of the priming apparatus, when starting the pumps, the vacuum pump builds up vacuum in the float chamber, the inlet chamber and the inlet pipe, and when the water rises to the inlet of the centrifugal pump it commences its pumping action. The water continues to rise and when it reaches a certain level it lifts the float and unseats the relief valve, thereby admitting air to the suction conduit and relieving the vacuum pump. When air is admitted to the suction conduit the check valve closes but air is free to flow through the small orifice 28 into the float chamber thereby slightly reducing the vacuum therein, but the float commences to close the relief valve as soon as the level of the water lowers in the float chamber, with the result that the vacuum pump promptly restores the vacuum in the float chamber and holds the level of the water therein substantially constant.

In the modified form illustrated in Figs. 4 and 5, the restricted orifice is provided around the valve stem 24 at the place where it passes through the wall 18 between the suction conduit and float chamber. In this case the orifice is formed by providing grooves 28 along the length l of the valve stem 24. As in the preferred form a small quantity of air is always free to flow from one side of the orifice to the other.

In the form illustrated in Fig. 6, the check valve 19 is formed with a small orifice 28 through which a small quantity of air is always free to flow.

I claim as new and desire to secure by Letters through which air is always free to flow.

2. In priming apparatus for centrifugal pumps, the combination of a centrifugal pump having an inlet connected to a lower level of water supply, a float chamber in communication with said inlet, a vacuum-pump having a suction conduit communicating with the float chamber through a valve controlled port, a relief valve for said suction conduit, and a float in said float chamber connected to and actuating said relief valve, there being a restricted orifice connecting the suction conduit with the float chamber through which air is always free to flow.

. 3. In priming apparatus for centrifugal pumps, the combination of a centrifugal pump having an inlet connected to a lower level of water supply, a float chamber above and in communication with said inlet, a vacuum pump having a suction conduit communicating with the upper end of the float chamber through a valve controlled port, a relief valve for said suction conduit, and

a float in said float chamber connected to said relief valve, there being a regulatable orifice connecting the suction conduit with the float chamber through which air is always free to flow.

4. In priming apparatus for centrifugal pumps, the combination of a centrifugal pump having an inlet connected to a lowenlevel of water supply, a float chamber in communication with said inlet, a vacuum pump having a suction conduit communicating with the float chamber through a'valve controlled port, a relief valve for said suction conduit, a float in said float chamber, and a valve stem extending through a wall between the float chamber and suction conduit and connecting the float to the relief valve, there being a restricted air passage around said valve stem extending from one side of said wall to the other, whereby air is always free to flow through said air passage.

5. In priming apparatus for centrifugal pumps,

the combination of a centrifugal pump having an inlet connected to a lower level of water supply, a chamber in communication with said inlet,

a vacuum pump having a suction conduit com municating with the chamber through a valve controlled port, and a relief valve for said. suction conduit, there being a restricted oriflceextending through the valve which controls the port between the chamber and suction conduit and continuously connecting the chamber with the suction conduit whereby air is always free to flow from one side to the other'of saidrestricted orifice.

6. In priming apparatus for centrifugal pumps, the combination of a centrifugal pump having an inlet chamber connected to a lower level of water supply, a float chamber above said inlet chamber and communicating directly with said inlet chamber through a narrow passage, a vacuum pump having a suction conduit communicating with said float chamber through a check valve controlled port, and a float operated relief valve for said suction conduit controlled by the level of water in the float chamber, there being a restricted orifice between the float chamber and suction conduit, through which air is always free to flow.

AUGUSTUS C. DURDIN, JR. 

